The Fantastic Four begin are stressing out over the fact that they do not know who their mysterious attacker is. When Reed turns up nothing, he recommends that Sue go and visit their son Franklin who is in the care of Agatha Harkness at her home in Whisper Hill. Richards continues to stress to his teammates that their foe is possibly the most dangerous they have ever faced. The FF are unaware that they are being monitored by Doctor Doom from his castle in upstate New York. When one of his minions brings him the recently stolen Horn of Proteus, he orders this minion to punish himself for interrupting him. Doom then begins the next phase of his plan, deciding to be ever more cautious in order to prevent his nemesis from deducing his involvement until it it too late.

Meanwhile, Reed, Johnny, and Ben pay a visit to Xavier's School for Gifted Youngers home of the X-Men. There Reed hopes he can utilize a pair of deactivated Sentinel robots to defend his family while they are trying to determine who their mystery attacker is. As Reed joins Professor X and Marvel Girl to see the Sentinels, Johnny and Ben accept a challenge to test out the X-Men's Danger Room. As Johnny and Ben join Havok, Lorna and Iceman in the Danger Room, the Beast and Reed go over the Sentinels and activate them. The Sentinels suddenly go berserk, smashing through the Danger Room floor and attacking the heroes inside. Before the Fantastic Four and the X-Men can shut these mutant hunting robots down, they smash through the wall and escape. At that same time, Sue and Crystal are on their way to Whisper Hill when suddenly the Inhuman's dog Lockjaw materializes inside their ship and teleports Crystal away.

At that moment, the Sentinels are headed to New York City with the X-Men and Fantastic Four en route. As the Sentinels descend on the city, they also attract the attention of Spider-Man, Daredevil, and Doctor Strange who join the fight against the sinister robots. During the course of the battle Spider-Man's Spider-Sense goes wild and he manages to warn them that the Sentinels are about to explode soon enough for Doctor Strange to place a fore field around them all to protect them from the blast. Meanwhile, back at the X-Men's mansion headquarters, Professor X and Marvel Girl have to hold off the Danger Room robot known as Colosso who has also been programmed to attack them. They then quickly destroy the robot, leaving them to wonder who their attacker was.

Not far away, Doctor Doom witnesses his latest scheme go to pot, and decides that acquiring Xavier's Cerebro device is not necessary to the success of his plans and continues onto the next phase, which he hope will destroy his hated enemy Reed Richards and the rest of the Fantastic Four.

Notes

Continuity Notes

Reed and Sue's son Franklin is said to be at the home of Agatha Harkness. At this point in time, Franklin was only recently born back in Fantastic Four Annual #6. The Fantastic Four hired Harkness as Franklin's babysitter, a role she took on from Fantastic Four #94-150. Agatha later left the Fantastic Four's employ to begin training the Scarlet Witch in the art of witchcraft in Avengers #128.

The deactivated Sentinels seen here were likely ones captured by the X-Men following their original encounter with the mutant hunting robots in X-Men #14-16. Chronologically, the X-Men previously clashed with the Sentinels in X-Men #57-59.